JPH06171490A - Antilock controller of electric automobile - Google Patents

Abstract

PURPOSE:To improve the controllability in the execution of antilock control in regard to an antilock controller of an electric automobile with two system brakes comprising both hydraulic and regenerative brakes. CONSTITUTION:This controller is provided with a first antilock control means A3, which executes antilock control for preventing any wheel lock by reducing the braking force in a brake means A1 on one side, and a second antilock control means A4, executing the antilock control over a brake means A2 on the other installed in an electric automobile, respectively. When the braking force of the brake means on one side canes to its decrease limitation by control operation of either of the first or second antilock control means A3 or A4, it is also provided with an antilock control adjusting means A5 which starts the antilock control by the antilock control means of the other side brake means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antilock control device for an electric vehicle, and more particularly to an antilock control device for an electric vehicle having two brake systems.

[0002]

2. Description of the Related Art In recent years, as a pollution-free vehicle, an electric vehicle that drives by driving electric motors (motors) with electric power charged in a battery and rotates wheels is attracting attention. Further, as a braking means of this electric vehicle, an electric braking method and a mechanical braking method are used together. This is because it is difficult to reliably brake the vehicle only by the electric braking method.

Here, the electric braking method is a method of braking the motor by converting kinetic energy of the motor into electric energy (electric power) and returning the electric energy (electric power) to a battery (hereinafter, this electric braking is performed. Means called regenerative braking). Further, the mechanical braking method is a braking method that has been conventionally adopted in a general engine vehicle, and is a method of directly braking a wheel by applying hydraulic pressure to a hydraulic brake (hereinafter, this mechanical braking method). The braking means is called a hydraulic brake).

On the other hand, an antilock control device is known as a device for controlling the braking of an automobile. This anti-lock control device is a device that performs braking control so that the wheels do not lock even when sudden braking is applied on a slippery road surface such as a snowy road.

A conventional anti-lock control device for performing anti-lock control on a vehicle equipped with these two systems of brakes (a regenerative brake and a hydraulic brake) is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-141354. There is something.

The anti-lock control device disclosed in the above publication is installed in an electric vehicle equipped with a regenerative brake and an air brake. The brake is a hydraulic brake and an air brake, and the vehicle is an electric vehicle and an electric vehicle. Although there are differences between cars, the basic braking principle is the same.

This anti-lock control device is constructed such that, when a wheel lock is detected, the regenerative brake is weakened and the air brake is held at a predetermined braking force, thereby suppressing the total braking force and locking. It was configured to prevent the occurrence. That is, the antilock control is executed substantially only for the regenerative brake, and the air brake for which the antilock control is not executed is controlled so as to maintain a predetermined braking force.

[0008]

On the other hand, a road surface on which a vehicle travels has various friction coefficients μ (hereinafter referred to as road surface μ), and there are cases where the road surface μ is extremely small such as a frozen road. In the antilock control when traveling on such a low μ road surface, it is necessary to greatly reduce the braking force.

However, in the above-described conventional antilock control device, only the regenerative brake performs the antilock control when the antilock control is executed, and a predetermined braking force is applied to the air brake. When the road surface μ is small, sufficient control characteristics cannot be obtained by anti-lock control using only regenerative braking, and therefore there is a problem that running stability and steering performance may be deteriorated due to wheel locking. there were.

The present invention has been made in view of the above points, and when one of the brakes of two systems has a limit of decrease, the other brake force is decreased to execute antilock control. It is an object of the present invention to provide an anti-lock control device for an electric vehicle that has improved controllability.

[0011]

FIG. 1 shows the principle of the present invention. In order to achieve the above object, as shown in the same figure, in the present invention, the drive motor drives the wheels to run, and the electric braking means (A1) and the second braking means (A2) are used as braking means. It is installed in an electric vehicle equipped with two braking means, and locks the wheels by controlling the two braking means (A1, A2) according to the locked state of the wheels during braking to increase or decrease the braking force. An anti-lock control device for an electric vehicle that prevents the lock of wheels by reducing the braking force of one of the two braking means (A1, A2) to reduce the braking force. A second anti-lock control for executing anti-lock control for preventing wheel lock by reducing the braking force of the first anti-lock control means (A3) for executing control and the remaining braking means (A2) Means (A4) and the first or second Anti-lock control means (A3, A4) When the braking force of one braking means reaches the limit of decrease due to the control operation of one of the anti-lock control means, the anti-lock control means of the other braking means An antilock control adjusting means (A5) for activating the control is provided.

[0012]

With the above structure, even if the braking force is reduced to the limit of reduction by one braking means, the braking force by the other braking means is reduced. The controllability of the antilock control can be improved as compared with the configuration that executes the lock control.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. 2 is a block diagram showing a braking system of an electric vehicle 1 to which an antilock control device according to an embodiment of the present invention can be applied, and FIG. 3 is a block diagram showing a control system of the antilock control device 2. is there. The overall configuration of the electric vehicle 1 will be described below with reference to FIGS. 2 and 3.

In FIG. 2, 3 to 6 are wheels, the front right wheel 3 is driven independently by a motor 7, and the front left wheel 4 is driven independently by a motor 8, and the rear right wheel 5 is driven.
The rear left wheel 6 and the rear left wheel 6 are driven by a motor 9 via a differential gear 10.

Further, reduction gears 11 to 13 are provided to the respective motors 7 to 9, and the reduction gears 11 to 13 are gears for reducing the rotation of the respective motors 7 to 9 and are used in general gasoline engines. It has the same function as a transmission in an automobile. Therefore, even with the motors 7 to 9 whose output torque is generally smaller than that of the gasoline engine, it is possible to obtain sufficient drive torque for traveling of the electric vehicle 1.

The motors 7-9 also function as regenerative brakes (hereinafter, when the motors 7-9 function as brakes, they will be referred to as regenerative brakes 7-9). That is, the rotational force of the wheels 3 to 6 is applied to the regenerative brakes 7 to 9 as kinetic energy during braking, but this kinetic energy is converted into electric energy (electric power) and returned to the battery 15 for each wheel. It is configured to perform braking on 3 to 6.

The motors (regenerative brakes) 7-9 are connected to a motor driver 14. The motor driver 14 controls each motor (regenerative brake) 7 to 9 in accordance with an instruction from the motor control ECU 30 (see FIG. 3). A battery 15 is connected to the motor driver 14, and the battery 1 is connected when the electric vehicle 1 is driven.
5, electric power is supplied to each of the motors 7 to 9 to drive the motors 7 to 9, and at the time of braking of the electric vehicle 1, the battery 15 is charged with the electric power generated by the regenerative brakes 7 to 9.

On the other hand, hydraulic brakes 16 to 19 are provided on the wheels 3 to 6, respectively. Each of the hydraulic brakes 16 to 19 has a brake cylinder, and the braking force is varied by the hydraulic pressure supplied to the brake cylinder. Also, the hydraulic brake 16-
Reference numeral 19 is connected to the ABS actuator 20. This ABS actuator 20 is a hydraulic brake ECU 31.
(See FIG. 3), the hydraulic brake ECU 3 is connected.
The hydraulic pressure supplied to each of the hydraulic brakes 16 to 19 is changed in accordance with the instruction No. 1, and the braking force of each wheel 3 to 6 is thereby controlled.

Reference numeral 21 in the drawing denotes a brake pedal,
It is operated by the driver when the electric vehicle 1 is braked. This brake pedal 21 is a booster 22
Also, the hydraulic pressure is connected to the master cylinder 23 and is supplied to the ABS actuator 20 with a hydraulic pressure according to the pedal effort of the driver. When the anti-lock control is not performed, the ABS actuator 20 operates the hydraulic brakes 16 according to the hydraulic pressure supplied from the master cylinder 23 according to the pedal effort of the driver.
It is configured to apply a hydraulic pressure to 19 to perform braking.

A brake pedal force sensor 24 and a brake switch 25 are attached to the brake pedal 21. This pedal depression force sensor 24 detects the depression force of the brake pedal 21 by the driver, and as shown in FIG.
This is transmitted to the motor control ECU 30 as a brake pedal force signal. Further, the brake switch 25 is a switch that detects whether or not the brake pedal 21 is being depressed, and when it is being depressed, it transmits a brake switch signal to the hydraulic brake ECU 31.

Wheel speed sensors 26 to 29 for detecting the wheel speeds of the respective wheels 3 to 6 are provided. The wheel speed sensors 26 to 29 are hydraulic brake ECUs.
The wheel speed of each wheel 3 to 6 is connected to the hydraulic brake ECU 31 as a wheel speed signal.

Next, the hardware configuration of the antilock control device 2 mounted on the electric vehicle 1 having the above configuration will be described with reference to FIG.

The antilock control device 2 is composed of the above-mentioned motor driver 14, ABS actuator 20, motor control ECU 30, hydraulic brake ECU 31 and the like. Among them, the motor control ECU 30 and the hydraulic brake ECU 31 are configured by a microcomputer, and include a microprocessor (MPU), a read only memory (ROM), a random access memory (RAM), a bus line connecting these, and an external device. I / for connecting with sensors and devices 14, 20, 24-29
It is composed of an O (Input / Output) unit and the like.

Antilock control device 2 according to the present embodiment
Is configured to perform antilock control on both the regenerative brakes 7-9 and the hydraulic brakes 16-19. Therefore, the antilock control is performed by the motor control ECU 3
0 and the hydraulic brake ECU 31. In addition, in the present embodiment, of the two ECUs 30 and 31 that execute antilock control, the antilock control executed by the motor control ECU 30 preferentially executes the process over the antilock control executed by the hydraulic brake ECU 31. Is configured. When the motor control ECU 30 is executing the antilock control, an ABS control flag signal that notifies the hydraulic brake ECU 31 of this is transmitted to the hydraulic brake ECU 31.

The anti-lock control executed by the anti-lock control device 2 will be described with reference to FIGS. 4 to 7.

The anti-lock control prevents the stability and steerability of the vehicle from being deteriorated when the brakes are suddenly applied on a slippery road surface such as a snowy road and the wheels 3 to 6 are locked and slip occurs. Therefore, the brake hydraulic pressure supplied to the hydraulic brakes 16 to 19 arranged on the wheels 3 to 6 is variably controlled, and the braking force is controlled so that the wheels 3 to 6 are not locked. Specifically, the following control operation is executed.

As described above, in the antilock control device 2 according to this embodiment, the motor control ECU 30 executes the antilock control prior to the hydraulic brake ECU 31.
Therefore, when the antilock control is executed, the motor control EC
U30 constantly monitors the rotation speeds of the wheels 3 to 6 based on the rotation speed signals transmitted from the rotation speed sensors 26 to 29 of the wheels 3 to 6.

Then, it is detected from the brake switch signal transmitted from the brake switch 25 that the brake pedal 21 is depressed (corresponding to time t1 in FIG. 4), and the wheel speed falls below the estimated vehicle speed. When the vehicle speed decreases to a speed at which slip may occur (hereinafter referred to as the slip speed) (corresponding to time t2 in FIG. 4), the motor control ECU 30 determines that the wheels 3 to 9 may be locked, and Start lock control. The motor control ECU 30 has four control modes (torque increasing mode, slow increasing mode, holding mode, and torque reducing mode) when executing the antilock control.
When the anti-lock control is started, first the motor control EC
U30 switches to the reduced torque mode (see FIG. 6 (A)).

Note that, as described above, the estimated vehicle body speed is calculated instead of the actual vehicle speed, and this is compared with the wheel speed to determine the start time of the antilock control. This is because it is difficult to accurately detect the vehicle speed of the vehicle.

When the motor control ECU 30 switches to the torque reduction mode, the motor control ECU 30 controls the motor driver 14 to reduce the regenerative torque for the regenerative motors 7-9. This reduces the braking force of each regenerative motor 7-9, prevents the wheels 3-6 from being locked, and maintains good stability and steerability of the vehicle. The above control corresponds to the control executed during the time t2 to t4 or t6 to t8 in FIGS. 6 (A) to 6 (C).

As described above, the braking force becomes smaller and the rotation speed of the wheels 3 to 6 increases as the regenerative torque is reduced. However, when the road surface μ on which the electric vehicle 1 travels is extremely small, it is necessary to greatly reduce the braking force in order to prevent the wheels 3 to 6 from being locked. ~ 6
In some cases, the braking force cannot be reduced enough to prevent the locking of the. FIG. 6C shows an example thereof. Although the torque reduction mode is set between times t2 and t4 in FIG. 6, the regenerative torque is already zero at times t3 and t7. The fact that the motor control ECU 30 maintains the torque reduction mode in spite of this indicates that sufficient antilock control cannot be performed only by reducing the braking force of the regenerative motors 7-9.

As described above, when sufficient antilock control cannot be performed only by reducing the braking force of the regenerative motors 7 to 9, the antilock control is performed by the hydraulic brake ECU 31, but for convenience of explanation, this hydraulic brake ECU is used.
The antilock control processing by 31 will be described later.

When the rotation speed of the wheels 3 to 6 exceeds a predetermined slip speed due to the execution of the torque reduction mode of the motor control ECU 30 and the anti-lock control processing by the hydraulic brake ECU 31 described later, the motor control ECU 30 causes the electric vehicle 1 to operate. It is determined that the state has started to recover from the locked state, and the mode is switched to the holding mode (see FIG. 6A). When the motor control ECU 30 switches to the holding mode, the motor control ECU 30 causes the motor driver 1
By controlling 4, the regenerative torque value at that time is maintained. The above control is performed at time t4 in FIGS. 6 (A) and 6 (C).
~ T5 or control executed during times t8 to t9. As described above, the figure shows an example in which it is sufficient to reduce the braking force of the regenerative motors 7 to 9, and therefore the regenerative torque in the holding mode is maintained at zero.

By executing the holding mode, the regenerative torque value is maintained for a predetermined time, and when the rotational speeds of the wheels 3 to 6 further increase and exceed the slip speed, the motor control ECU 30
Judges that there is no longer any risk of the wheels 3 to 6 being locked, and switches to the slow increase mode or torque increase mode. When the motor control ECU 30 switches to the slowly increasing mode or the increasing torque mode, the regenerative torque is increased and the strong braking force is applied to the wheels 3 to 6 again. The above control is performed at time t5 to t6 or time t9 to t1 in FIGS. 6 (A) and 6 (C).
This corresponds to the control executed during 0.

The two modes, the slow increase mode and the torque increase mode, are set as the modes for increasing the regenerative torque. The reason is that the degree of increase in the braking force can be selected from the two modes so that the rapid braking force is increased. This is to prevent an increase in

By repeatedly performing the antilock control operation described above by the motor control ECU 30,
~ 6 will be locked and slip will not occur,
It is possible to maintain the stability and steerability of the electric vehicle 1. In the above series of processing, the motor control ECU 30
The value of the regenerative torque set by is transmitted to the hydraulic brake ECU 31 as a motor regenerative torque signal (see FIG. 3).

In this embodiment, the antilock control is finished as follows. As shown in FIG. 7, when the increasing mode is continuously executed for a predetermined time (corresponding to time t13 to t14 in the figure), the motor control ECU
No. 30 is configured to terminate the antilock control when it is determined that the road surface does not require the antilock control. In the example shown in the figure, the anti-lock control ends at time t14.

Next, the antilock control operation by the hydraulic brake ECU 31, which is the subject matter of the present invention, will be described with reference to FIGS. 5 and 6.

FIG. 5 is a flow chart showing the antilock control processing of the hydraulic brake ECU 31. When the antilock control process shown in FIG.
In (hereinafter, step is abbreviated as S), the motor regenerative torque signal transmitted from the motor control ECU 30 is read.

In subsequent S12, the motor control ECU 30 determines whether or not the antilock control is being executed. As described above, when the motor control ECU 30 starts the antilock control, the ABS control flag signal is transmitted from the motor control ECU 30 to the hydraulic brake ECU 31. S
12, the motor control ECU 30 determines whether or not the motor control ECU 30 is currently in the antilock control based on the ABS control flag signal (the antilock control is described as ABS in the drawing).

If it is determined in S12 that the motor control ECU 30 is currently under antilock control, the process proceeds to S14. At S14, based on the motor regenerative torque signal read at S10, the current motor control E is performed.
The anti-lock control state of the CU 30 is judged. Specifically, it is determined whether the motor control ECU 30 is executing the torque reduction and the value of the regenerative torque is zero.

When a negative determination is made in S14, the process proceeds to S16, in which the hydraulic brake ECU 31 sets the brake hydraulic pressure supplied to the hydraulic brakes 16 to 19 so as to maintain the present hydraulic pressure, and the hydraulic pressure set in S16 is set. Is output to the ABS actuator 10. By this processing, each hydraulic brake 16 to 19 holds a predetermined braking force.

On the other hand, if an affirmative decision is made in S14, the processing advances to S18, in which the hydraulic brake ECU 31 sets the hydraulic pressure so that the brake hydraulic pressure supplied to each hydraulic brake 16-19 is reduced at a constant gradient, and S18 is set. The hydraulic pressure set in 1 is output to the ABS actuator 10. By this processing, the hydraulic brakes 16 to 19 gradually reduce the braking force.

The operation of the above-described processing of S10 to S20 will be described with reference to FIG. In the above process, S12 → S
The process that proceeds in the order of 14 → S16 → S20 indicates the process between times t2 to t3, t4 to t7, and t8 to t10 in FIG. Further, the processing that proceeds in the order of S12 → S14 → S18 → S20 shows the processing during the times t3 to t4 and t7 to t8 in FIG. That is, the hydraulic brake ECU 31 reduces the brake hydraulic pressure only when the motor control ECU 30 is executing the torque reduction by the antilock control and the value of the regenerative torque is zero, and does not change the brake hydraulic pressure in other states.

By this processing, even if the braking force of the regenerative brakes 7 to 9 is reduced to zero, which is the limit of reduction, by the anti-lock control of the motor control ECU 30, the hydraulic brakes ECU 31 at that time points to the hydraulic brakes 16 to 19.
Since the braking force of the electric vehicle 1 is reduced, the controllability of the antilock control can be improved as compared with the configuration in which the antilock control is executed only for the regenerative brakes 7 to 9, and the running stability and steering of the electric vehicle 1 are improved. It is possible to secure the sex.

Returning to FIG. 6 again, the description of the antilock control process will be continued. If it is determined in S12 that the antilock control is not currently executed, the process proceeds to S2.
Go to 2. In S22, it is determined whether or not the antilock control of the motor control ECU 30 has ended, and whether or not a predetermined time has elapsed after the end of the antilock control. The predetermined time referred to here corresponds to the time between times t14 and t15 in FIG. 7 (B). Further, the end of the antilock control by the motor control ECU 30 is configured to be determined based on the ABS control flag signal described above.

When a negative determination is made in S22, the process proceeds to S24, the brake hydraulic pressure is set to be increased with a constant gradient, and the set hydraulic pressure is output to the ABS actuator 20 in S20. By this processing, the hydraulic brakes 16 to 19 gradually increase the braking force. On the other hand, if an affirmative determination is made in S22, the process proceeds to S26, and the hydraulic control by the hydraulic brake ECU 31 ends.

The processes of S12 and S22 to S24 are processes at the end of the antilock control. By executing this process, as shown in FIG. 7 (B), the brake hydraulic pressure gradually rises, and the predetermined time period elapses. After a lapse of time, a constant brake hydraulic pressure is maintained. The predetermined time (the time between times t14 and t15) and the gradient of the pressure increase are configured to be the master cylinder pressure as the final brake hydraulic pressure by increasing the pressure for the predetermined time.

8 and 9 show various electric vehicles 32 and 33 to which the antilock control device 2 described above can be applied.
Is shown. In each drawing, the same components as those of the electric vehicle 1 shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

The electric vehicle 32 shown in FIG. 8 is of a type in which one motor 34 is arranged at the front of the vehicle and the left and right front wheels are driven. Further, the electric vehicle 33 shown in FIG. 9 has a structure in which the left and right front wheels are driven by the motor 35 arranged at the front of the vehicle and the left and right rear wheels are driven by the motor 36 arranged at the rear of the vehicle. is there. For electric vehicles with these various structures,
The antilock control device 2 of the present invention can be applied.

In the above embodiment, the motor control ECU 30 executes the antilock control prior to the hydraulic brake ECU 31. However, on the contrary, the hydraulic brake ECU 31 is not the same as the motor control ECU 3
The anti-lock control may be executed with priority over 0.

[0052]

As described above, according to the present invention, even if the braking force is reduced to the limit of reduction by one braking means, the braking force by the other braking means is reduced. The controllability of the antilock control can be improved as compared with the configuration in which the antilock control is executed only for the antilock control, and thus the stability and the steerability of the vehicle can be secured.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a diagram showing an overall structure of an electric vehicle to which an antilock control device according to an embodiment of the present invention is applied.

FIG. 3 is a block diagram showing a hardware configuration of an antilock control device according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining an antilock control method.

FIG. 5 is a flowchart showing a process performed by a motor control ECU during execution of antilock control.

FIG. 6 is a view showing a mode of a hydraulic brake ECU during execution of antilock control, a brake hydraulic pressure, and a regenerative torque in association with each other.

FIG. 7 is a view showing a mode of the hydraulic brake ECU at the end of antilock control, a brake hydraulic pressure, and a regenerative torque in association with each other.

FIG. 8 is a diagram showing another structure of an electric vehicle to which the present invention can be applied.

FIG. 9 is a diagram showing another structure of an electric vehicle to which the present invention can be applied.

[Explanation of symbols]

 1, 32, 33 Electric Vehicle 2 Antilock Control Device 3-6 Wheels 7-9, 34-36 Regenerative Brake (Motor) 10 Differential Gear 11-13 Reduction Gear 14 Motor Driver 15 Battery 16-19 Hydraulic Brake 20 ABS Actuator 21 Brake pedal 24 Pedal pedal force sensor 25 Brake switch 26-29 Wheel speed sensor 30 Motor control ECU 31 Hydraulic brake ECU

Claims (1)

[Claims] 1. A wheel is driven by a drive motor to travel, and the vehicle is provided with an electric vehicle having two braking means, an electric braking means and a second braking means, as braking means, and the wheel is driven during braking. An anti-lock control device for an electric vehicle, which controls locking of the wheels by controlling the two braking means to increase / decrease the braking force according to the locked state of the one of the two braking means. First anti-lock control means for executing anti-lock control for preventing the wheel from being locked by reducing the braking force of the braking means of the second wheel, and locking of the wheel by reducing the braking force of the remaining other braking means. Control of a second antilock control means for performing antilock control for preventing the above, and either one of the first or second antilock control means An electric vehicle provided with an anti-lock control adjusting means for activating an anti-lock control by an anti-lock control means of the other braking means when the braking force of one of the braking means reaches a reduction limit due to an operation. Anti-lock control device.